If you have the time and some decent weather on your drive to Islay taking a detour via the A817 between Loch Lomond and Gare Loch / Loch Long is well worth it. This view is on the western side, looking towards the Arrochar Alps. A biker is riding the other direction while my car is parked in a layby further down.
A view from the A817 on a journey to Islay in June 2018, not far from the view of the Arrochar Alps. The Navy base at Faslane can be seen below.
An early view from the A817 detour on the way to Islay (see also the view of the Arrochar Alps from the A817), looking back over Loch Lomond. It’s a fairly steep climb from the A82, but well worth it for the views.